Microchip Technology AT25256AW-10SI-1.8

Overview

AT25256AW-10SI-1.8 from Microchip Technology (formerly Atmel) is a 256 Kbit SPI serial EEPROM organized as 32,768 × 8 bits, operating from 1.8 V to 5.5 V with 20 MHz max clock rate at 5 V, 64-byte page write capability, and hardware/software write protection via WP and HOLD pins - deployed in industrial control systems for nonvolatile parameter storage.

For engineers reviewing the AT25256AW-10SI-1.8 datasheet, AT25256AW-10SI-1.8 pinout, AT25256AW-10SI-1.8 application, or AT25256AW-10SI-1.8 equivalent, key selection considerations include 1.8 V low-voltage operation, JEDEC SOIC-8 packaging, block write protection granularity (1/4, 1/2, full array), endurance of 100,000 write cycles, and automotive-grade temperature range (−40°C to +85°C).

Technical Context

The AT25256AW-10SI-1.8 implements a synchronous SPI slave interface compliant with Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1), with separate SI (input) and SO (output) pins and MSB-first data framing. It uses an 8-bit instruction register with op-codes for WREN, WRDI, RDSR, WRSR, READ, and WRITE.

Internal architecture includes a nonvolatile status register with BP0/BP1 for block protection and WPEN for hardware write protect enable/disable, plus automatic address incrementing during page writes and self-timed internal write cycles (≤5 ms). The HOLD pin suspends ongoing serial communication without resetting the sequence when asserted low during SCK low time.

Key Specifications

Pinout & Package

AT25256AW-10SI-1.8 is housed in an 8-lead JEDEC SOIC package (8S1), 0.150" wide body, with gull-wing leads and standard 1.27 mm pitch. Pin 1 is marked by a notch or dot; device orientation follows JEDEC MO-001AA.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with M95256-DWDW3TP/K and BR25H256FJ-WE2, AT25256AW-10SI-1.8 uniquely combines 20 MHz operation, functional HOLD pin, and JEDEC SOIC-8 packaging - making it optimal for industrial controllers needing fast, pausable, and pin-standard SPI configuration storage.

Availability

AT25256AW-10SI-1.8 is available at Aetrix Electronics and suitable for industrial PLCs, automotive ECUs, medical infusion pumps, smart utility meters, and embedded telemetry gateways requiring stable component supply across extended product lifecycles.

Supply support for AT25256AW-10SI-1.8 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology acquired Atmel in 2016 and continues to manufacture, qualify, and support the AT25xxx family of SPI EEPROMs with full backward compatibility and extended lifecycle commitments.

The AT25256AW-10SI-1.8 belongs to Microchip's industrial-grade serial EEPROM product line, designed specifically for robust, low-power, nonvolatile data storage in harsh environments where reliability, voltage flexibility, and SPI interoperability are critical.

FAQ

What is the maximum clock frequency supported by the AT25256AW-10SI-1.8 at 1.8 V?

The AT25256AW-10SI-1.8 supports up to 5 MHz SCK frequency when operating at 1.8 V, as specified in the AC Characteristics table under "1.8–5.5 V" voltage column. This ensures reliable timing margins for low-voltage microcontrollers while maintaining compatibility with the same instruction set used at higher voltages. The AT25256AW-10SI-1.8 maintains full functionality-including page write, status register access, and HOLD/WS protection-at this reduced speed.

Does the AT25256AW-10SI-1.8 require an external pull-up resistor on the SO pin?

No, the AT25256AW-10SI-1.8 does not require an external pull-up on the SO pin because it actively drives high or low during valid output periods and enters high-impedance state only when CS is high or HOLD is asserted. External pull-ups may cause bus contention or increased standby current and are explicitly discouraged in the datasheet. The AT25256AW-10SI-1.8 relies on proper CS and HOLD control for clean bus management.

How is block write protection configured on the AT25256AW-10SI-1.8?

Block write protection on the AT25256AW-10SI-1.8 is configured by writing to bits BP1 and BP0 in the status register using the WRSR instruction. Valid combinations are: 00 = no protection, 01 = top 1/4 (6000–7FFFh), 10 = top 1/2 (4000–7FFFh), and 11 = full array (0000–7FFFh). The AT25256AW-10SI-1.8 enforces protection immediately after WRSR completion and retains settings across power cycles.

Can the AT25256AW-10SI-1.8 be used in automotive applications requiring AEC-Q200 qualification?

Yes - the AT25256AW-10SI-1.8 is offered in automotive-grade variants (e.g., AT25256A-10SE-2.7) qualified to AEC-Q200 Rev D for extended temperature (−40°C to +125°C). While the -10SI-1.8 suffix denotes industrial grade (−40°C to +85°C), its construction, test flow, and reliability data derive from the same qualified platform. For full AEC-Q200 compliance, specify the -10SE or -10SQ suffix variants; the AT25256AW-10SI-1.8 remains suitable for under-dash automotive modules meeting industrial temp requirements.

What happens if the HOLD pin is asserted during an active AT25256AW-10SI-1.8 write cycle?

If the HOLD pin is asserted low during an internal write cycle (e.g., after CS goes high to initiate programming), the AT25256AW-10SI-1.8 ignores the HOLD signal - the write proceeds to completion in ≤5 ms. HOLD only affects serial communication (READ/WRITE instruction sequences), not ongoing self-timed internal operations. The AT25256AW-10SI-1.8 remains busy (RDY=1) until the write finishes, and RDSR remains accessible to monitor status.